Hermetically sealed detonator



Aug. 27, 1963 D. R. GATLEY ETAL 3,101,669

HERMETICALLY SEALED DETONATOR Filed Sept. 7, 1961 lq/ N m INVENTORS 7% @WMM ATTORNEYS United States Patent M 3,101,669 HERNIETlCALLY SEALED DETNA'R Derek R. Gatley, Windsor, and Walter L. Abigail, Staines, England, assignors of one-half to Graviner Muarinfaeturing Company Limited, and of one-halt to Wilkinson Sword Limited, both of London, England, and both British com anies Fileil Sept. 7, 1961, Ser. No. 136,634 Claims priority, application Great Britain Sept. 2l), 1960 3 Claims. (El. 1MP-28) This invention relates to electrically ignitable explosive charges or cartridges. t Y

According to the present invention there is provided an electrically ignitable explosive cartridge comprising a hollow metal body closed at one end, a ceramic insulator mounted in said body and having its outer peripheryhermeticallly sealed to the inner wall of said body, said. insulator having a portion of reduced size llocated adjacent Ithe closed end of the metal body, an ignitmg winding, wound on said portion of reduced size, the ends of said igniting winding being secured by solder to respective metallized portions of said insulator, and' explosive powder in the space between said reduced portion and the closed end of said metal body. c

One construction of electrically ignitabile lexplosive cartridge in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawing in which:

FlGURE l is a side elevation of the cartridge; and

'FIGURE 2 is a sectional plan view.

In this construction, the cartridge comprises a metal plug body of open-ended tubular-form. An annular internal ange 10a is located approximately one-third of the distance from one end of the plug body 1li and loicated against this flange lila and projecting from the latter end is a ceramic insulator 11. rlhis insulator .i1 has a -first portion `11a which lits in the plug body `1li and the periphery of this portion is metallized so that the ceramic insulator 11 can be secured to the plug body 10 by solder .12 applied between the periphery of the insulator 11 and the inner periphery of the plug body lili. The insulator l11 has a further relatively short-portion 11b of somewhat smaller diameter than the first portion 110i and' a third portion 111. The third portion :11e is coaxial with the two portions lila, 11b and its diameter is approximately one-third of that of the portion lla of the insulator `1l. Both the end surface 1101 of the smallest diameter portion llc and the annular surface jl-lbl formed by the step between the portions 1lb and 111C are metallized. A hole 11d is provided centrally through the insulator 11 and a second hole 11e is provided which extends through the two larger diameter portions i1-1n, 11b of the insulator 11 and has one end Aterminating in the metallized annular surface `1151.

An electrical igniting winding 13 is wound on the narrowest diameter portion lilo of the insulator .111 and one end of this Winding is connected to a lead wire 1d which extends through the central hole 11d in the insulator 11, the lead Wire 14 and the end of the winding '13 being electrically connected by solder 16 which is applied to the metallizing on the end surface lilcl. The solder lo serves also to form a hermetic seal `across the end of the central hole 11d. The other end of the winding 13 is similarly connected by solder .17 to a second lead wire which extends through the hole 11e in the insulator 11.

A tube 13 of insulating material rests on the step llal betwen the larger diameter portion `11a of the insulator and the adjacent smaller diameter portion :11b of the insulator 11 and provides a space around and beyond the end of the igniting winding 13, in which space the explosive powder 19 is packed. A rubbery sleeve 2u lits` y 3,101,669 Patented Aug. .27, 19613 over the tube 18 and closes the open end to complete an insulating enclosure around the powder. A metal outer sleeve 21 tits over this end of the cartridge, the outer sleeve having an integral end cap 21a, and extending rearwardly over the plug body 1) close lto the far end thereof. The outer sleeve 21 is sealed to the outer surface of the plug body by solder 22. i.

An linsulating moulding 2.3` lits the rear portion of the plug body [10 and carries two rearwardly projecting contact pins 2li by which external electrical connection is made to the igniting winding 13. The contact pins 24 are hollow and each receives one of the lead wires 14, 15, the end of each lead wire 14, 1S being eelctrically connected by solder 25 to the projecting end of the respective contact pins 24. The solder 25 also forms a hermetio seal across the end of each contact pin 14, '15. A washer 26 of insulating material seats within the internal ilange lila in the plug body 10 and is provided with holes therein through which the lead wires 51d, i15 pass; the holes and the adjacent space within the end of moulding 23 may be filled with hardenable synthetic-plastic insulating material 27.

It will be appreciated that the construction described provides a cartridge in which the explosive powder is completely hermetically sealed.

We claim: t

1. An electrically ignitable explosive cartridge comprising a hollow metal body, said body having one end closed, a ceramic insulator mounted within said body, said'insulator having an outer peripheral surface which -is metallized, said metallized surface being united by solder to said body, said insulator having a portion of reduced cross-sectional area terminating in a metalliz-.ed end surface which faces said body, said insulator also having a metallized annular surface at the step where the portion of reduced cross-sectional area abuts the remainder of the insulator, an electrical igniting winding, said winding being Wound on said portion of reduced cross-sectional area, explosive powder, said powder surrounding said igniting winding, said insulator having first and second holes extending through said insulator, said iirst hole terminating at said metallized annular surface and said secseal, and further solder adhering to said metallized end surface and electrically connecting the other end of the winding to said second lead wire, said further -solder extending across the second hole to form a seal.

.2. An electrically ignitable explosive cartridge comprising a cylindrical metal body, a metal sleeve, said sleeve extending partly over said body, said sleeve having an integral end cap, a ceramic insulator, said ceramic insulator having a irst cylindrical portion, said lirst cylindrical portion having a metallized periphery which is united by solder to said metal body, said ceramic insulator having a -second cylindrical portion of smaller diameter than said :first cylindrical portion, said insulator having a metallized annular surface at the step from the first cylindrical portion to the second cylindrical portion and the second cylindrical portion having a metallized end surface remote from said annular surface, an electrical igniting winding, said Winding having two ends and being wound on said second cylindrical portion with one winding end adjacent said metallized annular surface and the other winding end adjacent said metallized end surface, explosive powder, said explosive powder lying within the interior of said metal sleeve and around said igniting winding, said insulator having hrst and second holes extending through said insulator, said rst hole terminating at said metallized annular surface and said second hole terminating at said metallized end surface, lirst and second lead Wires extending through said -rst and second holes respectively, solder adhering to said metallized annular surface and electrically connecting said one winding end to said first lead wire, further solder adhering to the said metallized end surface and electrically connecting said other winding end to said second lead Wire, a further insulating member, said further insulating member being mounted in said metal body remote from the closed end rof said sleeve, two tubular contact pins, said contact pins being mounted in said further insulating member, each of said lead wires passing through the interior of one of s'aid contact pins, and solder sealing across the interior of leach of said contact pins and electrically connecting the contact pins to the respective lead wires.

3. An electrically ignitable explosive cartridge comprising a cylindricalr metal body, a metal sleeve, said sleeve extending partly over said body, said sleeve having an integral end cap, a ceramic insulator, -said ceramic insulator having a first cylindrical portion, said first cylindrical portion having a metallized periphery which is united by solder to said metal body, said ceramic insulator having a second cylindrical portion of smaller diameter than said iirst cylindrical portion, said insulator having a metallized annular surface at the step from the first cylindrical 4 portion to the second cylindrical portion and the second cylindrical portion having a metallized end surface remote from said annular surface, an electrical igniting winding, said winding having two ends and being wound on said second cylindrical portion with one winding end adjacent said metallized annular surface and theother winding end adjacent said metallized end surface, explosive powder, said explosive powder lying within the interior of said metal -sleeve and around said igniting winding, said insulator having first and second holes extending throughusaid insulator, said rst hole terminating at said metallized annular surface and said second hole terminating at said metallized end surface, iirst and second lead wires extending through said first `and second holes respectively, solder adhering to said metallized annular surface and electrically connecting said one winding end to said 4first lead wire, and further solder adhering to the said metallized end surface and electrically connecting,

said other winding end tosaid second lead wire.

References Cited in the le of this patent UNITED STATES PATENTS 2,240,438 Durant Apr. 29, 1941 2,882,820 Young Apr. 21, 1959 FOREIGN 'PATENTS i 579,123 Great Britain July 24, 1946 

1. AN ELECTRICALLY IGNITABLE EXPLOSIVE CARTRIDGE COMPRISING A HOLLOW METAL BODY, SAID BODY HAVING ONE END CLOSED, A CERAMIC INSULATOR MOUNTED WITHIN SAID BODY, SAID INSULATOR HAVING AN OUTER PERIPHERAL SURFACE WHICH IS METALLIZED, SAID METALLIZED SURFACE BEING UNITED BY SOLDER TO SAID BODY, SAID INSULATOR HAVING A PORTION OF REDUCED CROSS-SECTIONAL AREA TERMINATING IN A METALLIZED END SURFACE WHICH FACES SAID BODY, SAID INSULATOR ALSO HAVING A METALLIZED ANNULAR SURFACE AT THE STEP WHERE THE PORTION OF REDUCED CROSS-SECTIONAL AREA ABUTS THE REMAINDER OF THE INSULATOR, AN ELECTRICAL IGNITING WINDING, SAID WINDING BEING WOUND ON SAID PORTION OF REDUCED CROSS-SECTIONAL AREA, EXPLOSIVE POWER, SAID POWER SURROUNDING SAID IGNITING WINDING, SAID INSULATOR HAVING FIRST AND SECOND HOLES EXTENDING THROUGH SAID INSULATOR, SAID FIRST HOLE TERMINATING AT SAID METALLIZED ANNULAR SURFACE AND SAID SECOND HOLE TERMINATING AT SAID METALLIZED END SURFACE, FIRST AND SECOND LEAD WIRES EXTENDING THROUGH SAID FIRST AND SECOND HOLES RESPECTIVELY, SAID WINDING HAVING TWO ENDS, SOLDER ADHERING TO SAID METALLIZED ANNULAR SURFACE AND ELECTRICALLY CONNECTING ONE WINDING END TO SAID FIRST LEAD WIRE, SAID SOLDER EXTENDING ACROSS THE FIRST HOLE TO FORM A SEAL, AND FURTHER SOLDER ADHERING TO SAID METALLIZED END SURFACE AND ELECTRICALLY CONNECTING THE OTHER END OF THE WINDING TO SAID SECOND LEAD WIRE, SAID FURTHER SOLDER EXTENDING ACROSS THE SECOND HOLE TO FORM A SEAL. 